Bio measuring meters applied for detecting substances contained in blood to be analyzed, such as glucose or cholesterol, use a disposable sample strip. The sample strip has a reaction zone allowing blood to be placed thereon. The operation is controlled by a microprocessor. By execution of various methods, analysis results of the measurement are obtained.
For processing the sample measurement and the analysing routines the bio measuring meter needs certain parameter values which determine thresholds, time intervals, control numbers and calibration curve attributes.
Usually it is necessary to calibrate measuring devices in order to compensate for variations from lot to lot of the manufactured sample strip. Various techniques have been suggested for encoding information into the sample strip, as disclosed by U.S. Pat. No. 5,053,199 and references cited therein. This may e.g. be electronically encoded information on a carrier having an optical bar code, a magnetizable film, a perforated strip, a fluorogens or an electrically conductive medium on a foil.
Each of such known sample strips has to be furnished with an in-formation code, which is an additional manufacturing step and thus an expensive effort for a disposable device.
Other conventional measuring meters use an additional coding module or code key designed and inserted into a receptacle similar to the slot for the sample strip.
When performing a measurement, the memory key has to be inserted in the measuring meter before using a new batch of sample strips. Preferably the coding module remains inserted during the measurement or even all the time for the same batch of sample strips.
Based on the data or the code provided by the coding module the operation method, parameters or algorithms are chosen and a correct measurement result is obtained.
U.S. Pat. No. 5,366,609 and documents cited therein disclose bio measuring meters which have pluggable ROM coding modules that enable re-configuration of test methods and parameters employed by the meter. Threshold potentials, test times, delay periods and other pertinent test methods and constants may be entered and/or altered.
The main purpose of the coding module still is to provide information about the type of sample strip. For each new batch of sensor strips, new related information is needed.
As sample strips are disposable, preferably coding modules are disposable too. Costs for the module are therefore an important factor.
In a co-pending application, a coding module and bio measuring meter are presented, wherein the code is represented by a parameter value of an electrical component having a determined characteristic, such as a resistor or a capacitor. In comparison with the use of integrated circuits, the use of electrical components reduces the complexity and cost of the design. Thus, some of the drawbacks of the state of the art are overcome. However, the costs due to components and fabrication are still relatively high. Furthermore, electrical components present a risk of being influenced by a contamination of biological samples. Cleaning of such a code key is not easily feasible.
It is therefore an object of the invention to overcome the drawbacks of the prior art, especially to avoid the usage of memory IC chip technology for storing codes on coding modules, and to provide a coding module, a set of coding modules, a method for producing a coding module, a bio measuring meter with pluggable coding module, a bio measuring system, a bio measuring test set and a method for operating a bio measuring meter, which are not sensible with regard to a pollution caused by a biological sample and which can be produced cost-effectively.